From MozillaZine Knowledge Base



Normally, scrolling with the mousewheel will scroll the entire page. If the mouse cursor is over a scrollable element on the page, that element will scroll instead, until it can scroll no more, and then the entire page will continue scrolling. However, this can be disruptive if a user is scrolling a page and happens to mouseover another scrollable element (e.g., a form select dropdown or multi-line text field). Conversely, if a user is scrolling through a dropdown or text field and hits the top or bottom, having the entire page start moving again can be annoying.

To address these common cases, every use of the mousewheel is considered a “transaction.” Within a transaction, only one element is scrolled, whether it be the entire page or a dropdown menu. If the mouse cursor moves after scrolling, the transaction is automatically ended unless the movement occurs within the amount of time specified by this preference.

Possible values and their effects

An integer determining the number of milliseconds after a mousewheel scroll during which mouse movement that could end the transaction should be ignored. Default value is 100 (a tenth of a second).

First checked in

2006-07-11 by Masayuki Nakano

Has an effect in

  • Mozilla Firefox (nightly builds since 2006-07-11)
  • SeaMonkey (nightly builds since 2006-07-11)

Related bugs

Related preferences